GB2413339A

GB2413339A - Lost shuttering having walls of expanded metal mesh

Info

Publication number: GB2413339A
Application number: GB0408963A
Authority: GB
Inventors: Tony Killarney; Tom Sexton
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-04-22
Filing date: 2004-04-22
Publication date: 2005-10-26
Also published as: GB0408963D0

Abstract

Device 1 for forming a concrete foundation has a frame 2 comprising posts 6 supporting bars 4. Sheet material 10 covers the frame and comprises a layer of expanded metal mesh (12, fig 3) sandwiched between two layers of metal grids (14, 16, fig 3). The frame 2 may be rectangular with a post 6 at each corner, preferably supporting five spaced transverse bars 4. The bars and posts may be metallic, preferably steel. The sheet material 10 may comprise a single bent sheet welded to the frame 2. The two grids (14, 16) preferably comprise spaced parallel bars and may be arranged transversely to each other. The mesh (12) may be welded between the two grids. In use, concrete may be poured into the excavated hole (24, fig 6) outside of the formwork 1 to secure it, preferably some concrete is poured into the formwork 1 to form a base (26, fig 6) before a support leg (22, fig 6), e.g. for a pylon, is introduced and the formwork is filled with concrete (28, fig 6).

Description

Formwork Device and Method The present invention relates to a formwork

device and method and, in particular, to a formwork device for facilitating the formation of a concrete foundation, and a method of using the device to form a concrete foundation, for a support leg of a tower structure, such as a pylon, stanchion or the like.

One known method of installing and supporting pylons in a concrete foundation involves excavating a hole for each support leg of the pylon and driving steel sheets down around the periphery of each hole. Each support leg is then located in a corresponding hole and concrete is poured into the hole and set to embed the leg.

However, such a sheet piling method is cumbersome to use since the sheets are large and heavy. In addition, when the process has been completed, the pylon obstructs subsequent withdrawal of the steel sheets.

However, the principal problem with this method is the inherent danger for workers since typically workers have to enter the hole to facilitate location of the support leg, yet the sheet piling can be prone to collapse.

Another known method involves the use of a hollow concrete pipe which is placed within the excavated hole. The support leg is then located within the pipe and concrete is poured into the pipe and set to embed the leg.

* e . J be. e e e v' e ee Although such concrete pipes are safer and stronger than steel piling, so that this method protects workers from the risk of collapse, it is not a practical solution. The pipes are very heavy, are generally dangerous to guide into position and typically require large machinery to manoeuvre and install them in the holes.

The present invention has been made from a consideration of the disadvantages associated with such known methods and in order to provide a formwork device and improved method, which may overcome one or more of the above-mentioned disadvantages. In particular, the invention seeks to provide a formwork device and method, which is convenient and cost and labour efficient to use, yet which has a high safety rating.

According to a first aspect of the invention there is provided a formwork device for forming a concrete foundation comprising a frame having an open top and bottom structure and comprising a plurality of bars arranged in substantially parallel spaced apart relationship extending around and defining the periphery of the frame, the bars being supported on a plurality of upright posts, and sheet material extending around and secured to the exterior of the frame wherein the sheet material comprises first and second metal grid layers with a layer of expanded metal mesh therebetween. a a

a a c a -e s. $ $ a a ca ë e a $ a a sea äa Preferably, the frame is substantially rectangular and an upright post is provided at each corner edge thereof.

Preferably, the upright posts support five transverse bars, one bar being supported substantially centrally on the upright posts and the other bars being supported on the upright posts adjacent the respective top and bottom of the frame.

Preferably, the upright posts are secured to an outer surface of the bars. Preferably, the bars and the upright posts comprise metal, preferably steel.

Preferably, the sheet material is welded to the upright posts. Preferably, the sheet material comprises a single sheet which is bent to extend continuously around the frame.

Preferably, the first grid comprises a series of spaced apart elongate parallel rods extending in a first direction and the second grid comprises a series of spaced apart elongate parallel rods extending in a second direction transversely to the first direction and the layer of expanded mesh is welded between the rods of the first and second grids.

According to a second aspect of the invention there is provided a method of fixing a support leg in a concrete foundation comprising the steps of locating a formwork device of the invention in an excavated hole, pouring concrete into a spacing between external faces of the device and the excavation, positioning a support leg e . eve e .. e e . . within the formwork device and filling the hole within the formwork device with concrete.

Preferably, the method includes pouring a layer of concrete blinding into the hole through the formwork device before positioning the support leg.

The invention will now be described further, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a formwork device according to an embodiment of the invention located in an excavated hole in the ground; Fig. 2 is a perspective view of the formwork device of figure 1 with the spacing between the external faces of the device and the excavation filled with concrete and with a concrete blinding in the hole; Fig. 3 is a front view showing the construction of the sheet material used in the formwork device of the invention; and Fig. 4 is a cross-sectional view through an excavated hole showing a formwork device of the invention in use.

Referring to figure 1, a formwork device 1 according to one embodiment of the invention comprises a substantially rectangular frame 2 defined by a plurality of spaced apart horizontal bars 4 extending around the periphery of the frame and supported on a plurality of upright posts 6.

. . . :.:: :.-:. ..:: a

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The frame has an open top and bottom structure.

Typically, each horizontal bar 4 comprises a single bar which extends continuously completely around the frame.

Typically the horizontal bars 4 and the upright posts 6 comprise metal, preferably steel.

In the embodiment illustrated, four upright posts 6 are provided, one at each corner edge of the frame 2, and these support three horizontal bars 4. In a preferred embodiment, five such horizontal bars are provided. One horizontal bar 4 is supported substantially centrally on the upright posts 6 and the other horizontal bars 4 are supported on the upright posts 6 adjacent the respective top and bottom of the frame. Typically, the upright posts 6 are secured, by welding or other suitable means, to an outer surface of the horizontal bars 4.

Sheet material 10 extends around the exterior of the frame 2 and is welded or otherwise bonded to the frame at appropriate locations, typically to the upright posts 6. Typically, the sheet material 10 comprises a single sheet which is bent to shape around the frame 2 and extends continuously completely around the frame.

Referring to figure 3, the sheet material 10 comprises first and second outer layers of metal, typically steel, grids with a layer of expanded metal mesh 12 sandwiched therebetween. The first grid comprises a series of spaced apart elongate parallel rods 14 extending in a first direction or longitudinally and the second grid comprises a series of spaced apart . . . . . . .. . . elongate parallel rods 16 extending in a second direction transversely to the first direction or horizontally. The central layer of expanded mesh 12 is welded between the longitudinal and horizontal rods 14, 16 of the outer layers.

It will be appreciated that the formwork device of the invention may have any suitable cross-sectional shape, for example rectangular, square, elliptical or circular. A suitable number of upright posts 6 is used to form the frame 2 depending on the selected shape and the horizontal bars 4 are shaped to extend around and define the periphery of the frame.

In use, in a particular application to install, for example, a power cable pylon the following method is typically employed.

Referring to figures 1 and 4, a hole 20 is excavated for receiving a pylon support leg 22. The prefabricated formwork device 1 is placed centrally into the excavated hole using suitable machinery and the formwork device is aligned and positioned as required.

Referring to figures 2 and 4, structural concrete 24 is then poured into the spacing between the external faces of the formwork device 1 and the excavation 20. A small layer, typically about lOOmm, of concrete blinding 26 is then poured into the hole through the formwork device 1 and allowed to cure for, typically, about twelve hours.

. . . . ë e . . ... . The support leg 22 is then positioned within the formwork device 1 and aligned and levelled. The hole within the formwork device is then filled or partly filled with concrete 28 and sets to form the foundation.

Using the formwork device of the invention, continuity is maintained between the outer concrete 24, of the spacing between the external faces of the formwork device and the excavation, and the inner concrete 28, within the formwork device, since, in use, slurry flows through the expanded metal mesh 12 of the formwork device. Thus, the structure of the sheet material 10 is such as to provide the surface required for aggregate interlock between adjoining concrete forms.

Thus, the invention provides a formwork device and method, which is easy and cost and labour efficient to use, yet which has a high safety rating. The formwork device of the invention is relatively light and strong and can be easily and safely manocuvred into position.

The device provides improved safety by eliminating risk, including the risk of collapse, to workers during use. The device allows concrete to be poured around the outside of the device first so that it is then safe for workers to get into the excavated hole to set and position the support leg before pouring concrete inside the formwork device.

Furthermore, although in general reinforcements, such as reinforcing steel bars, are required between adjacent concrete sections, with the formwork device . . . . ë e. ë . . . and method of the invention such reinforcements are not required.

Although the formwork device and method of the invention is particularly suitable for use in forming a concrete foundation for a support leg of a tower structure, such as a pylon, the invention may be used in a variety of applications, such as to form concrete pockets for roller coaster support legs or similar rides; to form air/water relief pockets to caissons on a bridge construction; or to form concrete pockets for stanchions to support signs or the like.

It will be appreciated that expressions of orientation

or direction used in the present specification,

including the claims, such as top, bottom, upright, exterior etc. are used for convenience only and refer to the normal orientation of the formwork device relative to the ground in use and as seen in the accompanying drawings. However, such expressions are not to be regarded as limiting the orientation of the formwork device in use.

It will be appreciated that the present invention is not intended to be restricted to the details of the above embodiment, which is described by way of example only.

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Claims

Claims 1. A formwork device for forming a concrete foundation comprising

a frame having an open top and bottom structure and comprising a plurality of bars arranged in substantially parallel spaced apart relationship extending around and defining the periphery of the frame, the bars being supported on a plurality of upright posts, and sheet material extending around and secured to the exterior of the frame wherein the sheet material comprises first and second metal grid layers with a layer of expanded metal mesh therebetween.
2. A formwork device according to claim 1 wherein the frame is substantially rectangular and an upright post is provided at each corner edge thereof.
3. A formwork device according to any preceding claim wherein the upright posts support five transverse bars, one bar being supported substantially centrally on the upright posts and the other bars being supported on the upright posts adjacent the respective top and bottom of the frame.
4. A formwork device according to any preceding claim wherein the upright posts are secured to an outer surface of the bars.

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5. A formwork device according to any preceding claim wherein the bars and the upright posts comprise metal, preferably steel.
6. A formwork device according to any preceding claim wherein the sheet material is welded to the upright posts.
A formwork device according to any preceding claim wherein the sheet material comprises a single sheet which is bent to extend continuously around the frame.
8. A formwork device according to any preceding claim wherein the first grid comprises a series of spaced apart elongate parallel rods extending in a first direction and the second grid comprises a series of spaced apart elongate parallel rods extending in a second direction transversely to the first direction and the layer of expanded mesh is welded between the rods of the first and second grids.
9. A method of fixing a support leg in a concrete foundation comprising the steps of locating a formwork device according to any preceding claim in an excavated hole, pouring concrete into a spacing between external faces of the device and the excavation, positioning a support leg within the formwork device and filling the hole within the formwork device with concrete. .

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10. A method according to claim 9 further including the step of pouring a layer of concrete blinding into the hole through the formwork device before positioning the support leg.

A formwork device for forming a concrete foundation substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

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